Air movement devices such as ceiling fans, extractor fans and the like, conventionally have a number of extending fan blades which rotate at varying speeds. The fan blades radiate from a central hub portion and the hub is connected to a shaft which is driven by an electric motor.
These fans suffer from two main disadvantages. Firstly, ceiling fans are dangerous because of the circulating metallic fan blades. There are numerous cases of injury to children which come into contact with the fan blades. Similarly, children have been injured by inserting fingers into wall fans.
The second main disadvantage with these fans is that they suck air from an area immediately above the blades. That is, air is not drawn directly into the blades and therefore moved by the blades from positions other than immediately above the blades. This lack of efficiency is particularly problematic with exhaust fans positioned above stoves. Typically, these exhaust fans only exhaust a small portion of air directly below the fan but do not readily draw air in from any other position.
Additionally, it is difficult to provide heating or cooling devices in association with large bladed fans as such an arrangement is extremely inefficient. Providing a smaller bladed fan (such as that found with small fan heaters), is also not efficient as the volume of the moved air is low, and the smaller fans are extremely localised.
Another disadvantage with ceiling fans is that by their design they are not suitable, and indeed can be extremely dangerous when attached to low ceilings as it is common for a conventional ceiling fan to be spaced from a ceiling by up to 50 cm.